Evaluating anchor variables and variation in meaningful score differences for PROMIS® Pediatric measures in children and adolescents living with a rheumatic disease.

PURPOSE: Meaningful score differences (MSDs), as defined by recent FDA guidance, can improve the interpretation of outcome measure scores and score changes. Well-accepted methods for estimating MSDs typically rely on external anchor variables, but the applications of these methods are limited in children and adolescents with rheumatic diseases. This project explored multiple candidate anchors for the PROMIS® Pediatric measures of Physical Activity, Fatigue, Pain Interference, and Mobility for children with juvenile idiopathic arthritis (JIA) or systemic lupus erythematosus (SLE). METHODS: Longitudinal data were extracted from the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry. Candidate anchors included patient-reported domain-specific global impressions of change (GIC) along with other parent- and clinician-reported variables. Prior to MSD estimation, the quality of the anchors was assessed using a priori criteria (correlation ≥0.30, n≥10, <10% missing). Anchors meeting criteria were used to calculate MSDs. RESULTS: Among 289 children with JIA and 47 with SLE, the GIC did not meet criteria inhalf of the scenarios. Other candidate anchors performed slightly better. The calculated MSDs varied by external anchor across measures, diagnoses, and direction of change (better vs worse). CONCLUSIONS: Many of the candidate external anchoring variables did not meet pre-specified criteria for calculating MSDs. Even for those that did, the choice of anchoring variable had a strong impact on the estimated MSD value and were different from other published values. As in adults, establishing pediatric MSDs requires selection of high-quality anchors, as changes in the variables used as anchors can impact MSD values and any subsequent score interpretations.

Identifying clinically meaningful severity categories for PROMIS pediatric measures of anxiety, mobility, fatigue, and depressive symptoms in juvenile idiopathic arthritis and childhood-onset systemic lupus erythematosus.

PURPOSE: A key limitation to widespread adoption of patient-reported outcome (PRO) measures is the lack of interpretability of scores. We aim to identify clinical severity thresholds to distinguish categories of no problems, mild, moderate, and severe along the PROMIS® Pediatric T-score metric for measures of anxiety, mobility, fatigue, and depressive symptoms for use in populations with juvenile idiopathic arthritis (JIA) and childhood-onset systemic lupus erythematosus (cSLE). METHODS: We used a modified standard setting methodology from educational testing to identify clinical severity thresholds (clinical cut scores). Using item response theory-based parameters from PROMIS item banks, we developed a series of clinical vignettes that represented different severity or ability levels along the PROMIS Pediatric T-score metric. In stakeholder workshops, participants worked individually and together to reach consensus on clinical cut scores. Median cut-score placements were taken when consensus was not reached. Focus groups were recorded and qualitative analysis was conducted to identify decision-making processes. RESULTS: Nine adolescents (age 13-17 years) with JIA (33% female) and their caregivers, five adolescents (age 14-16 years) with cSLE (100% female) and their caregivers, and 12 pediatric rheumatologists (75% female) participated in bookmarking workshops. Placement of thresholds for bookmarks was highly similar across stakeholder groups (differences from 0 to 5 points on the PROMIS t-score metric) for all but one bookmark placement. CONCLUSION: This study resulted in clinical thresholds for severity categories for PROMIS Pediatric measures of anxiety, mobility, fatigue, and depressive symptoms, providing greater interpretability of scores in JIA and cSLE populations.

Lenalidomide for refractory cutaneous manifestations of pediatric systemic lupus erythematosus.

Objective Cutaneous manifestations of pediatric systemic lupus erythematosus cause significant morbidity. Lenalidomide, a thalidomide analogue, has shown promise treating cutaneous lupus erythematosus in adults. Our objective was to evaluate lenalidomide's efficacy and safety in treating refractory cutaneous manifestations of pediatric systemic lupus erythematosus. Methods We performed a retrospective chart review of 10 adolescents who received lenalidomide for recalcitrant cutaneous lupus erythematosus. Information was gathered at drug initiation and 6-month follow-up. The Wilcoxon matched-pairs signed-rank test was used to assess change in quantitative parameters of disease activity. Results Nine subjects were girls and six were African-American. Indications for lenalidomide treatment included alopecia, nasal and oral ulcers, extensive malar rash, discoid lesions, bullous lesions, panniculitis, cutaneous vasculitis, and Raynaud's phenomenon with digital ulcerations. Within 6 months, all patients demonstrated complete or near resolution based on physician report. Prednisone dose decreased from a mean 23.5 mg (SD± 13.3) to 12.25 mg (SD± 9.2) ( P= 0.008). Sedimentation rate decreased from a mean 29 mm/hour (SD± 31.5) to 17 mm/hour (SD± 18.1) ( P= 0.004). Lenalidomide was well tolerated. Conclusion Lenalidomide is an effective and safe treatment for a spectrum of dermatological conditions in pediatric systemic lupus erythematosus. Its use may allow a reduction in prednisone dose and decreased disfigurement. Prospective study is needed to clarify lenalidomide's role in treating cutaneous manifestations of systemic lupus erythematosus.

Severe disease presentation and poor outcomes among pediatric systemic lupus erythematosus patients in South Africa.

Background Systemic lupus erythematosus (SLE) is a life-threatening multisystem autoimmune disease that is more severe in patients of African ancestry and children, yet pediatric SLE on the African continent has been understudied. This study describes a cohort of pediatric SLE (PULSE) patients in South Africa. Methods Patients with a diagnosis of SLE (1997 American College of Rheumatology criteria) diagnosed prior to age 19 years in Cape Town, South Africa, were enrolled in this cross-sectional study from September 2013 to December 2014. Information on clinical and serological characteristics was extracted from medical records. Results were compared to a well-described North American pediatric SLE cohort. Results Seventy-two South African patients were enrolled in the study; mean age 11.5 years; 82% were girls. The racial distribution was 68% Coloured, 24% Black, 5% White and 3% Asian/Indian. Most patients presented with severe lupus nephritis documented by renal biopsy (61%). Of patients with lupus nephritis, 63% presented with International Society of Nephrology/Renal Pathology Society class III or IV. Patients in the PULSE cohort were more likely to be treated with cyclophosphamide, methotrexate and azathioprine. The PULSE cohort had high disease activity at diagnosis (mean Systemic Lupus Erythematosus Disease Activity Index-2K (SLEDAI-2K) 20.6). The SLEDAI-2K at enrolment in the PULSE cohort (5.0) did not differ from the North American pediatric SLE cohort (4.8). Sixty-three per cent of the PULSE cohort had end organ damage with Systemic Lupus International Collaborating Clinics Damage Index (SLICC-DI) score >0 (mean SLICC-DI 1.9), compared to 23% in a previously reported US cohort. Within the PULSE cohort, nine (13%) developed end-stage renal disease with six (8%) requiring transplant, strikingly higher than North American peers (transplant rate <1%). Conclusions The PULSE cohort had highly active multiorgan disease at diagnosis and significant disease damage at enrolment in the South African registry. South African patients have severe lupus nephritis and poor renal outcomes compared to North American peers. Our study revealed a severe disease phenotype in the PULSE cohort resulting in poor outcomes in this high-risk population.

Annexin A5 anticoagulant activity in children with systemic lupus erythematosus and the association with antibodies to domain I of ß2-glycoprotein I.

Children with systemic lupus erythematosus (SLE) have a high prevalence of antiphospholipid (aPL) antibodies and are at increased risk for aPL-related thrombosis. We investigated the association between annexin A5 anticoagulant activity and antibodies to the domain I portion of ß2-glycoprotein I (anti-DI antibodies), and propose a potential mechanism for the pathogenesis of aPL-related thrombosis. Using samples from 183 children with SLE collected during the Atherosclerosis Prevention in Pediatric Lupus Erythematosus (APPLE) trial, we examined resistance to the anticoagulant effects of annexin A5, using the annexin A5 resistance (A5R) assay, and evaluated for anti-DI IgG antibodies. Children with SLE had higher frequency of anti-D1 antibodies (p = 0.014) and significantly reduced A5R compared to pediatric controls: mean A5R = 172 ± 30% versus 242 ± 32% (p < 0.0001). Children with SLE and positive anti-DI antibodies had significantly lower mean A5R levels compared to those with negative anti-DI antibodies: mean A5R = 155 ± 24% versus 177 ± 30% (p < 0.0001). In multivariate analysis, anti-DI antibodies (p = 0.013) and lupus anticoagulant (LA) (p = 0.036) were both independently associated with reduced A5R. Children with SLE have significantly reduced annexin A5 anticoagulant activity that is associated with the presence of LA and anti-DI antibodies.

Use of atorvastatin in systemic lupus erythematosus in children and adolescents.

OBJECTIVE: Statins reduce atherosclerosis and cardiovascular morbidity in the general population, but their efficacy and safety in children and adolescents with systemic lupus erythematosus (SLE) are unknown. This study was undertaken to determine the 3-year efficacy and safety of atorvastatin in preventing subclinical atherosclerosis progression in pediatric-onset SLE. METHODS: A total of 221 participants with pediatric SLE (ages 10-21 years) from 21 North American sites were enrolled in the Atherosclerosis Prevention in Pediatric Lupus Erythematosus study, a randomized double-blind, placebo-controlled clinical trial, between August 2003 and November 2006 with 36-month followup. Participants were randomized to receive atorvastatin (n=113) or placebo (n=108) at 10 or 20 mg/day depending on weight, in addition to usual care. The primary end point was progression of mean-mean common carotid intima-media thickening (CIMT) measured by ultrasound. Secondary end points included other segment/wall-specific CIMT measures, lipid profile, high-sensitivity C-reactive protein (hsCRP) level, and SLE disease activity and damage outcomes. RESULTS: Progression of mean-mean common CIMT did not differ significantly between treatment groups (0.0010 mm/year for atorvastatin versus 0.0024 mm/year for placebo; P=0.24). The atorvastatin group achieved lower hsCRP (P=0.04), total cholesterol (P<0.001), and low-density lipoprotein (P<0.001) levels compared with placebo. In the placebo group, CIMT progressed significantly across all CIMT outcomes (0.0023-0.0144 mm/year; P<0.05). Serious adverse events and critical safety measures did not differ between groups. CONCLUSION: Our results indicate that routine statin use over 3 years has no significant effect on subclinical atherosclerosis progression in young SLE patients; however, further analyses may suggest subgroups that would benefit from targeted statin therapy. Atorvastatin was well tolerated without safety concerns.

Laboratory markers of cardiovascular risk in pediatric SLE: the APPLE baseline cohort.

As part of the Atherosclerosis Prevention in Pediatric Lupus Erythematosus (APPLE) Trial, a prospective multicenter cohort of 221 children and adolescents with systemic lupus erythematosus (SLE) (mean age 15.7 years, 83% female) underwent baseline measurement of markers of cardiovascular risk, including fasting levels of high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides (TG), lipoprotein A (Lpa), homocysteine and high-sensitivity C-reactive protein (hs-CRP). A cross-sectional analysis of the baseline laboratory values and clinical characteristics of this cohort was performed. Univariable relationships between the cardiovascular markers of interest and clinical variables were assessed, followed by multivariable linear regression modeling. Mean levels of LDL, HDL, Lpa, TG, hs-CRP and homocysteine were in the normal or borderline ranges. In multivariable analysis, increased Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), prednisone dose, and hypertension (HTN) were independently associated with higher LDL levels. Higher hs-CRP and creatinine clearance were independently related to lower HDL levels. Higher body mass index (BMI), prednisone dose, and homocysteine levels were independently associated with higher TG levels. Only Hispanic or non-White status predicted higher Lpa levels. Proteinuria, higher TG and lower creatinine clearance were independently associated with higher homocysteine levels, while use of multivitamin with folate predicted lower homocysteine levels. Higher BMI, lower HDL, and longer SLE disease duration, but not SLEDAI, were independently associated with higher hs-CRP levels. The R(2) for these models ranged from 7% to 23%. SLE disease activity as measured by the SLEDAI was associated only with higher LDL levels and not with hs-CRP. Markers of renal injury (HTN, proteinuria, and creatinine clearance) were independently associated with levels of LDL, HDL, and homocysteine, highlighting the importance of renal status in the cardiovascular health of children and adolescents with SLE. Future longitudinal analysis of the APPLE cohort is needed to further examine these relationships.

Management of dyslipidemia in children and adolescents with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an independent risk factor for atherosclerosis, placing children and adolescents with SLE at great risk for developing cardiovascular sequelae, including myocardial infarction, in adulthood. Dyslipidemia and other traditional cardiac risk factors occur frequently in pediatric SLE and are often under-recognized and under-treated. Two dyslipidemia patterns are evident in pediatric SLE. Active disease is characterized by elevated triglycerides (TG) and low high density lipoprotein (HDL). With SLE treatment HDL and TG often normalize, while total cholesterol and low density lipoprotein (LDL) rise. The complex pathophysiology of dyslipidemia in SLE involves cytokines, autoantibodies, disease activity, medications, diet, and physical activity level, as well as other factors. Routine screening for dyslipidemia with fasting lipid profiles is indicated for children and adolescents with SLE. If lipoprotein levels are abnormal, first line therapy involves diet and exercise interventions for a minimum of six months. For persistent dyslipidemia, several pharmacologic therapies are available. Hydroxychloroquine, a common treatment for SLE, can improve lipid profiles and should be considered for all patients with SLE. Statins and bile acid sequestrants are typically added first for dyslipidemia, while niacin and fibrates are reserved for refractory disease and optimally prescribed in a multidisciplinary lipid clinic. Future research is needed to further illuminate the mechanisms of dyslipidemia in pediatric SLE with well designed clinical trials to determine the safest and most effective interventions to correct lipid profiles and prevent atherosclerosis.

Family pain history predicts child health status in children with chronic rheumatic disease.

OBJECTIVES: To examine the relationships of parental and family pain history on the pain experience of children with chronic rheumatic disease. The aims of the study were as follows: 1) to describe the pain history of parents and families of children with rheumatic disease, 2) to examine relationships between parental and family pain history and the pain report and physician-rated health status of children with chronic rheumatic disease, and 3) to determine whether child coping mediates the relationship between family pain history and the child's pain and physician-rated health status. METHOD: Parents of 100 children were recruited from a pediatric rheumatology clinic during routine visits. Parents completed questionnaires assessing parental pain history and family characteristics. Children in the study completed a series of questionnaires to assess pain and pain coping strategies, including the Coping Strategies Questionnaire and parts of the Pediatric Pain Questionnaire. A pediatric rheumatologist provided a global assessment of disease severity on a 100-mm visual analog scale as an index of child health status. RESULTS: A high number of parents of children seen in a pediatric rheumatology clinic described a personal pain history. More than 90% of parents reported having at least 1 chronic pain condition, with an equal proportion reporting an episode of pain in the past month. The most commonly reported pain conditions were lower back pain, shoulder/neck pain, and migraine headache pain. On average, this group of parents reported a history of 3.5 chronic pain conditions (standard deviation: 2.3) and reported having sought treatment for 1.7 (standard deviation: 2.3) of these conditions. Additionally, 93% of all parents reported extended family members experiencing at least 1 chronic pain condition. Correlational analyses indicated that parents reporting higher levels of current pain and higher mean levels of pain during the past month were more likely to have children reporting higher levels of current pain (r = 0.23 and r = 0.27). In addition, parents who sought more treatment for their own pain were more likely to have children reporting higher levels of pain (r = 0.22) and presenting with poorer health status (r = 0.22). Similarly, parents reporting higher levels of pain-related interference with activity were more likely to have children reporting higher levels of current pain (r = 0.23). Correlational analyses also indicated that children whose extended families reported a history of multiple pain conditions were more likely to report higher levels of current pain (r = 0.24) and more pain locations (r = 0.23). Finally, a series of mediational statistical models confirmed that child use of the pain coping strategy, catastrophizing, partially accounted for the relationship between several parent and family pain history variables and the child's own current pain ratings and physician global assessment. Specifically, child catastrophizing mediated the relationships between the total number of treated pain conditions and children's current pain ratings and physician global assessment. In addition, child catastrophizing was shown to mediate the relationship between parental mean level of pain in the past month and children's current pain rating and the relationship between total number of family pain conditions and children's current pain rating. Taken together, our results suggest that parental and familial pain experiences predict children's use of catastrophizing to cope with pain, which in turn predicts physician global assessment and children's current pain. CONCLUSIONS: The results from the present study indicate that many of the parents of children seen in a pediatric rheumatology clinic have a personal pain history and highlight the potential impact of parental pain history on children's pain experiences. Specifically, parents who were more likely to seek treatment for their own pain or more likely to report interference with recreational activities because of pain had children with higher pain ratings and poorer health status as measured by the physician global assessment. Additionally, a series of mediational models showed that child catastrophizing serves as a specific mechanism through which parental and familial pain history variables influence child ratings of current pain and physician ratings of health status. Future studies are needed to determine exactly how children living in families with painful conditions become more reliant on catastrophizing to cope with their pain. In addition, more research is needed to identify other potential mediators, such as positive ways parents may influence children's pain coping. There are several important clinical implications of our findings. First, our results suggest that by gathering information from parents about their own pain histories, health care providers may be able to identify children at risk for developing maladaptive pain coping strategies and higher levels of disease-related pain and disability. Second, our results indicate that intervention programs should focus specifically on reducing children's use of catastrophizing to cope with their pain. Perhaps most importantly, our results highlight the need to include parents in interventions aimed at reducing children's pain and improving children's abilities to cope with pain.

Juvenile primary fibromyalgia syndrome.

Juvenile primary fibromyalgia syndrome (JPFS) is a common musculoskeletal pain syndrome of unknown etiology characterized by widespread persistent pain, sleep disturbance, fatigue, and the presence of multiple discrete tender points on physical examination. Other associated symptoms include chronic anxiety or tension, chronic headaches, subjective soft tissue swelling, and pain modulated by physical activity, weather, and anxiety or stress. Research and clinical observations suggest that JPFS may have a chronic course that impacts the functional status and psychosocial development of children and adolescents. In addition, several factors have been implicated in the etiology and maintenance of JPFS including genetic and anatomic factors, disordered sleep, psychological distress, and familial and environmental influences. A multidisciplinary approach to treatment of JPFS is advocated, including pharmacologic and nonpharmacologic interventions (eg, psychotherapy, aerobic exercise, sleep hygiene).

The relationship of daily mood and stressful events to symptoms in juvenile rheumatic disease.

OBJECTIVES: The purpose of this study was 3-fold: 1) to assess the feasibility of a daily diary for use with children with juvenile rheumatic disease (JRD), 2) to describe daily variation in mood, stressful events, and symptoms in children with JRD, and 3) to examine the extent to which daily mood and daily stressful events predict daily symptoms in children with JRD. METHODS: Twelve children with JRD completed a daily booklet for 7 days. The daily booklet included measures of daily mood, daily stressful events, daily symptoms, and daily function. The children also completed a visual analog scale for pain and the Children's Depression Inventory. RESULTS: Subjects showed good compliance with scheduled completion and return of the daily diaries. Results indicated that children with JRD showed variability in daily mood, frequency of daily stressful events, and daily symptoms across days. Multilevel fixed effects models showed that more negative daily mood and more daily stressful events significantly predicted increased reports of fatigue, stiffness, and cutting back on daily activities. Negative daily mood also correlated with increases in daily reported pain. CONCLUSIONS: These results indicate that daily diary research is both feasible and potentially informative in children with JRD. Our data emphasize the need for further investigation into the role of daily mood and daily stressful events on disease course in JRD.

Prevention of leg length discrepancy in young children with pauciarticular juvenile rheumatoid arthritis by treatment with intraarticular steroids.

OBJECTIVE: To determine if intraarticular (i.a.) injection of triamcinolone hexacetonide (steroids) used early in the course of pauciarticular juvenile rheumatoid arthritis (pauci JRA) is associated with less leg length discrepancy (LLD) or thigh circumference discrepancy (TCD). METHODS: Children with pauci JRA who had asymmetric lower-extremity arthritis diagnosed before age 7 years in Seattle, Washington (WA; n = 16) and in Chapel Hill and Durham, North Carolina (NC; n = 14) were retrospectively identified. WA children were given i.a. steroids within 2 months of diagnosis; the injections were repeated if synovitis recurred in the same joint or in a different joint. These children were compared with NC children who were not treated with i.a. steroids. Thigh circumference was measured at 10 cm above the patella, and leg length was measured from the anterior superior iliac spine to the mid-medial malleolus, by a single observer. LLD and TCD are reported as the percentage of difference between leg measurements in each subject. RESULTS: The WA and NC subjects had comparable disease severity and duration of followup (in months). Twelve WA children had subsequent i.a. steroid injections (mean 3.25 injections per child over mean +/- SD 42 +/- 11 months). The WA subjects had significantly less LLD (P = 0.005, by Student's 2-sided t-test) and prescriptions for shoe lifts (P = 0.002, by Fisher's 2-sided exact test). There was not a significant difference in TCD between the 2 groups (P = 0.139, by Student's 2-sided t-test). Similar findings were obtained when the analysis was limited to children with monarticular knee arthritis. CONCLUSION: Early and continued use of i.a. steroids may be associated with less LLD in young children with pauci JRA. This may indicate decreased duration of synovitis.

Causes of pain in children with arthritis.

Pain in children with juvenile rheumatoid arthritis (JRA) is often not fully recognized and is therefore incompletely treated. The use of pain assessment instruments developed specifically for children may enhance recognition by health care providers. Recent studies suggest that coping variables and disease severity are significant predictors of pain in children with JRA. Pain in children with JRA is a complex phenomenon, best managed using a multidisciplinary approach that includes aggressive traditional medical management and addresses psychosocial variables such as coping strategies and perceptions about disease.

Social context of pain in children with Juvenile Primary Fibromyalgia Syndrome: parental pain history and family environment.

OBJECTIVE: The purpose of this study was to describe parental pain history and the family environment as it relates to the functional status of children with Juvenile Primary Fibromyalgia Syndrome (JPFS). DESIGN AND OUTCOME MEASURES: Twenty-nine parents of children with JPFS completed a pain history questionnaire, Von Korff Chronic Pain Grading system, and the Family Environment Scale (FES). Twenty-one adolescents with JPFS completed the FES, the Visual Analogue Scale for Pain, the modified Fibromyalgia Impact Questionnaire for Children, the Arthritis Impact Measurement Scales, and the Symptom Checklist-90-Revised. Correlational analyses were performed. RESULTS: Parents of children with JPFS reported multiple chronic pain conditions, including but not limited to fibromyalgia. Parental pain history and the family environment correlated with the health status of adolescents with JPFS. Children with JPFS perceived the family environment as significantly more cohesive than did their parents. Greater incongruence between parent and child responses on the FES positively correlated with greater impairment. CONCLUSIONS: These results suggest that family environment and parental pain history ày be related to how children cope with JPFS. Behavioral interventions targeting the family may improve the long-term functional status of children with JPFS.

Pain coping strategies in children with juvenile primary fibromyalgia syndrome: correlation with pain, physical function, and psychological distress.

OBJECTIVES: The purpose of this study was twofold: 1) to describe the coping strategies used by children with juvenile primary fibromyalgia syndrome (JPFS), and 2) to examine how pain coping relates to measures of pain, disability/function, psychological distress, and pain behavior. METHODS: Sixteen children with JPFS completed the Child Version of the Coping Strategies Questionnaire (CSQ-C), the visual analog scale for pain, the McGill Pain Questionnaire, the Fibromyalgia Impact Questionnaire modified for children, the Arthritis Impact Measurement Scales 2, and the Symptom Checklist-90-Revised. Subjects also also underwent pain behavior observation. Pearson's product moment correlations were conducted to examine the relationship of coping to measures of pain and disability. RESULTS: The Pain Control and Rational Thinking composite factor score on the CSQ-C correlated with measures of pain severity, functional disability, and psychological distress. Results supported the internal reliability of the CSQ-C in assessing pain coping. CONCLUSIONS: These results suggest that the CSQ-C may provide a reliable measure for assessing variations in pain coping in JPFS patients. Behavioral interventions aimed at increasing the perception of pain control may be beneficial in treating JPFS.

The mouse CD7 gene: identification of a new element common to the human CD7 and mouse Thy-1 promoters.

Human CD7 (hCD7) is a 40 000 Mr member of the immunoglobulin gene superfamily that is expressed early in natural killer (NK) and T-lymphocyte development. CD7 is involved in lymphocyte activation, as ligation of CD7 activates NK and TCRgammadelta T lymphocytes, and ligation of CD7 on TCRalphabeta T lymphocytes induces a non-mitogenic calcium flux. We have previously cloned and characterized the gene for human CD7 (hCD7) and have described its expression in transgenic mice. Recently a mouse cDNA homologous to hCD7 was reported, which we mapped to the corresponding mouse chromosomal location as hCD7. We now report the identification and characterization of a mouse CD7 (mCD7) genomic clone. We demonstrated that the mCD7 gene was similar both in size and structural organization to hCD7. Comparison of the 5' flanking sequences of the mCD7 and hCD7 genes revealed two regions of sequence similarity. Electrophoretic mobility shift assay confirmed both of these regions to be sites of tissue-restricted protein binding in vitro. The more 3' similarity region also shared sequence with a region in the mouse Thy-1 gene 5' flanking region, suggesting that this sequence may be a cis-acting regulatory element common to all three genes. Thus, the promoter regions and exonic organization were similar in the human CD7, mouse CD7, and mouse Thy-1 genes.

Characterization of human CD7 transgenic mice.

CD7 is a 40-kDa transmembrane glycoprotein member of the lg gene superfamily expressed on most peripheral blood T lymphocytes and NK cells. CD7 is also expressed on myeloid, NK, B, and T cell precursors during adult hematopoiesis. Because Thy-1 is absent in human thymocytes and peripheral blood T cells and shows structural similarities to the human CD7 gene, we have suggested that human CD7 may be a functional homologue in humans of mouse Thy-1. To study the tissue-specific expression of the CD7 gene utilizing its own promoter, we constructed transgenic mice that contained both the coding and flanking regions of the human CD7 gene. We found that human CD7 was expressed in transgenic mice in T, B, NK, and myeloid lineages and was induced with T cell activation. Unlike the expression of CD7 in humans, the CD7 transgene was present on mature B lymphocytes and macrophages. Like mouse Thy-1, transgenic human CD7 was expressed in immature and mature T cells and in Sca-1+ bone marrow mononuclear cells. Unlike mouse Thy-1, the human CD7 transgene was not expressed in mouse brain or fibroblasts. The human CD7 transgene was expressed during fetal development before mouse Thy-1 in fetal liver mononuclear cells. Expression of the human CD7 transgene did not alter mouse thymopiesis or Thy-1 expression. Taken together, these data demonstrated that the CD7 transgene contained sufficient regulatory regions to direct hematopoietic expression and mitogenic induction. The pattern of CD7 transgene expression more closely resembled that of CD7 in humans than that of mouse Thy-1.

Isolation and characterization of the genomic human CD7 gene: structural similarity with the murine Thy-1 gene.

The human CD7 molecule is a 40-kDa member of the immunoglobulin gene superfamily that is expressed on T-lymphoid and myeloid precursors in fetal liver and bone marrow. CD7 is also expressed on T lymphocytes in multiple stages of T-cell development, including a major subset of mature peripheral T cells. In this paper we report the isolation and characterization of the human CD7 gene and 5' flanking region. Sequence analysis revealed that the CD7 gene comprises four exons that span 3.5 kilobases. The 5' flanking region (506 base pairs) has a high G + C content and no "TATA" or "CCAAT" elements. DNase I sensitivity analysis of chromatin from the CD7+ progenitor cell leukemia line, DU528, and the CD7-, CD4+, CD8+, TCR alpha beta + T-cell line, DU980 (where TCR is the T-cell receptor), revealed two distinct hypersensitive sites 5' of the CD7 gene. Hypersensitive site 1, present in the DU980 T-cell line, was located 4.5 kilobases upstream of the presumed CD7 transcription initiation site. Only DNase I hypersensitive site 2, which mapped to the promoter region, was found in the DU528 line. Comparison of the organization of the CD7 gene with that of other members of the immunoglobulin gene superfamily revealed that the human CD7 gene most closely resembles the murine Thy-1 gene. Both CD7 and Thy-1 are encoded by small genes with four exons, contain TATA-less promoters, and have a similar functional organization. These structural similarities suggest that human CD7 and murine Thy-1 may be functional homologues.